How much time in San Gimignano when side tripping from Florence

We spent about three hours there, you could spend more or less depending on what interests you. It's a cute little town, some cute shops, I liked the church there.

We spent about the same time Nadine did, an early lunch, a little shopping, took in the view from the tower. You can stock up on water and whatever at the little market outside the towns walls more reasonably than inside.

We spent about 3 hrs there as well, which I think is plenty. But that didn't include a meal. We walked all over, including the residential area (always my favorite area of a town). It was extremely HOT when we were there which meant we walked slower than usual.

Agree that a half day was enough. It's lovely but there's just not a whole lot to do and the town is small enough to walk basically from end to end in just a couple of hours.

I agree with everyone, 2 to 3 hours is about enough time to walk around, buy souvenirs and have gelato. If you want to sit down for a meal, add another hour. It's fascinating to just wander around in San G. It has these narrow medieval roads that they allow cars in and it's pretty funny to see a traffic light there, the traffic light was so anachronistic.

Be sure to have lunch there at least. There are some good restaurants and with no street traffic, the cafes are very pleasant.

I'd either plan morning to an early lunch or later afternoon (sorry, early dinners don't exist in Italy). Several hours is about right, especially if you can miss the most crowded part of the day.